Development of ultrasensitive indium oxide layer with high response to NO2 gas in indium gallium zinc oxide stack structure using atomic layer deposition

•An indium gallium zinc oxide (IGZO) film was deposited in a stack structure.•The IGZO film was used as a sensing layer for NO2 detection.•The sensor exhibited excellent NO2-detection, selectivity, and repeatability. An indium gallium zinc oxide (IGZO)-based sensor was fabricated using atomic layer deposition (ALD) to detect NO2 gas. A unique IGZO film with a thickness of approximately150nm was deposited to form a stack structure (ZnO/Ga2O3/In2O3) at 150 °C. The sensor was annealed under an O2 atmosphere at 500 °C for 1 h. The annealing of the stack structure resulted in an exceptionally active In2O3 sensing layer on top of a Zn/Ga oxide layer, which significantly enhances the sensing performance. Using In2O3 on the top of the stack shows a higher sensor response compared with using ZnO as the top layer. The highest response (i.e., S (Rgas/Rair), ~8000, where Rair is the standby resistance in air and Rgas is the resistance upon exposure to an oxidizing gas) was obtained at 200 °C. The constructed sensor showed excellent NO2 detection performance, selectivity, and repeatability.